There are two types of frame structures in a long-term evolution (LTE) system. Frame structure type 1 is applicable to frequency division duplex (FDD) and frequency division half-duplex. Each radio frame has a length of 10 ms, and is composed of 20 time slots, wherein each time slot is 0.5 ms, and these time slots are numbered from 0 to 19. FIG. 1 is a schematic diagram showing the frame structure of an FDD mode according to the relevant technology. As shown in FIG. 1, one subframe is composed of two continuous time slots, e.g. subframe i is composed of two continuous time slots 2i and 2i+1. No matter half-duplex FDD or full-duplex TDD, uplink and downlink transmission are implemented at different frequencies. However, as regards half-duplex FDD, a UE cannot transmit and receive data simultaneously, while such limit does not exist in full-duplex FDD, i.e. 10 downlink and 10 uplink subframes may exist at every interval of 10 ms.
Frame structure type 2 is applicable to time division duplex (TDD). FIG. 2 is a schematic diagram showing the frame structure of a TDD mode according to the relevant technology. As shown in FIG. 2, a radio frame has a length of 10 ms, and is composed of two half-frames with the length being 5 ms. One half-frame is composed of 5 subframes with the length being 1 ms. The supported uplink and downlink configurations are as shown in Table 1. In the table, “D” represents that the subframe is a downlink subframe; “U” represents that the subframe is an uplink subframe; and “S” represents that the subframe is a special subframe. The special subframe is composed of a DwPTS, a guard period (GP) and an UpPTS, and the total length is 1 ms. Each subframe i is composed of two times slots 2i and 2i+1 with the length being 0.5 ms (15360×Ts).
Frame structure type 2 supports two downlink-uplink conversion periods of 5 ms and 10 ms. In the uplink and downlink conversion period of 5 ms, both of the two half-frames have the special subframe. In the uplink and downlink conversion period of 10 ms, only the first half-frame has a special subframe. Subframes 0 and 5 and the DwPTS are always reserved for downlink transmission. The UpPTS and the subsequent subframe closely next to the special subframe are always reserved for uplink transmission. Therefore, as regards the uplink and downlink conversion period of 5 ms, the UpPTS, subframe 2 and subframe 7 are reserved for uplink transmission; and as regards the uplink and downlink conversion period of 10 ms, the UpPTS and subframe 2 are reserved for uplink transmission.
TABLE 1Uplink and downlink configurationsUplink andDownlink-downlinkto-uplinkconfig-conversionSubframe numberurationsperiod012345678905 msDSUUUDSUUU15 msDSUUDDSUUD25 msDSUDDDSUDD310 ms DSUUUDDDDD410 ms DSUUDDDDDD510 ms DSUDDDDDDD65 msDSUUUDSUUD
The following three downlink physical control channels are defined in LTE: a physical control format indicator channel (PCFICH), a physical hybrid automatic retransmission request indicator channel (PHICH) and a physical downlink control channel (PDCCH).
Information borne on the PCFICH is used for indicating the number of orthogonal frequency division multiplexing (OFDM) symbols for transmitting the PDCCH in one sub frame. The information is transmitted on the first OFDM symbol of the subframe, and the frequency location thereof is determined by system downlink bandwidth and cell identity (ID).
The PHICH is used for bearing acknowledgement/non-acknowledgement (ACK/NACK) feedback information of uplink transmission data. The number and time-frequency location of the PHICH may be determined by a system message in a physical broadcast channel (PBCH) of a downlink carrier where the PHICH is located and cell ID.
The PDCCH is used for bearing downlink control information (DCI), including: uplink PUSCH scheduling information, downlink PDSCH scheduling information and uplink power control information.
As regards FDD, when a UE detects in subframe n a PDCCH channel which bears PUSCH scheduling information and belongs to the UE, or the UE receives in subframe n a PHICH corresponding to the PUSCH which belongs to the UE, the UE will transmit PUSCH data in subframe n+4 according to situations.
As regards TDD uplink and downlink configurations 1-6, when a UE detects in subframe n a PDCCH channel which bears PUSCH scheduling information and belongs to the UE, or the UE receives in subframe n a PHICH corresponding to the PUSCH which belongs to the UE, the UE will transmit PUSCH data in subframe n+k according to situations. As regards TDD uplink and downlink configuration 0, when a UE detects in subframe n a PDCCH channel which bears PUSCH scheduling information and belongs to the UE and the high bit of UL Index signalling in the scheduling information is 1, or when the UE receives in subframe 0 a PHICH corresponding to the PUSCH which belongs to the UE and subframe 5 and IPHICH=0, the UE will transmit PUSCH data in subframe n+k according to situations. When a UE detects in subframe n a PDCCH channel which bears PUSCH scheduling information and belongs to the UE and the low bit of UL Index signalling in the scheduling information is 1, or when the UE receives in subframe 0 and subframe 5 a PHICH corresponding to the PUSCH which belongs to the UE and IPHICH=1, the UE will transmit PUSCH data in subframe n+7 according to situations. The value of k above is as shown in Table 2.
TABLE 2Schematic table of values of k corresponding to TDD configurations 0-6TDD Uplink anddownlinkDownlink subframe number nconfigurations01234567890464616464244344444454677775
When the PUSCH is transmitted on subframe n, the UE will detect corresponding PHICH resources on downlink subframe n+kPHICH. As regards FDD, kPHICH is 4, and as regards TDD, kPHICH is determined according to Table 3.
TABLE 3Schematic table of values of kPHICH corresponding to TDDTDD Uplink anddownlinkUplink subframe index nconfigurations0123456789047647614646266366646656646647
As regards FDD, PDSCH ACK/NACK transmitted on downlink subframe n−4 is fed back on uplink subframe n. As regards TDD, PDSCH ACK/NACK transmitted on downlink subframe n−h is fed back on uplink subframe n, where hεK, and K is defined in Table 4.
TABLE 4Downlink subframe set corresponding to TDD K: {k0, k1, . . . kM−1}TDD Uplink anddownlinkSubframe number nconfigurations01234567890——6—4——6—41——7, 64———7, 64—2——8, 7, 4, 6————8, 7, 4, 6——3——7, 6, 116, 55, 4—————4——12, 8, 7, 116, 5, 4, 7——————5——TBD———————6——775——77—
Since the LTE-Advanced network needs to be able to access an LTE user, its operation frequency band needs to cover the present LTE frequency band. On this frequency range, there is no allocable continuous frequency spectrum bandwidth of 100 MHz, and thus one direct technique needing to be solved in LTE-Advanced is to aggregate several continuous component carriers (CCs) (frequency spectrums) distributed on different frequency ranges using the technique of carrier aggregation, forming bandwidth of 100 MHz capable of being used by LTE-Advanced. That is to say, as regards an aggregated frequency spectrum, it is divided into n component carriers (frequency spectrums), and the frequency spectrum inside each component carrier (frequency spectrum) is continuous.
As regards the problem of relatively low frequency spectrum utilization of data transmission in carrier aggregation scenarios in multiple different systems in the relevant technology, there is still no effective solution proposed at present.